The Discovery of Oxygen The Discovery of Oxygen Zuse Konrad Who Discovered Oxygen? Everyone needs oxygen to survive � man and animals alike. Furthermore, oxygen is the third most abundant element in the universe and makes up nearly 21% of the earth's atmosphere. Oxygen accounts for nearly half of the mass of the earth's crust, two thirds of the mass of the human body and nine tenths of the mass of water. In this page we will try to outline the path to the discovery of this important substance. Oxygen was discovered for the first time by a Swedish Chemist, Carl Wilhelm Scheele , in 1772. Joseph Priestly , an English chemist, independently, discovered oxygen in 1774 and published his findings the same year, three years before Scheele published. Antoine Lavoisier , a French chemist, also discovered oxygen in 1775, was the first to recognize it as an element, and coined its name "oxygen" - which comes from a Greek word that means �acid-former�. There is a historic dispute about who discovered oxygen. Most credit Priestly alone or Both Priestly and Scheele.

To learn more about this dispute go to the link section, at the bottom of this page. Famous Experiments Oxygen from Minerals In 1772, Carl Wilhelm Scheele discovered that red-hot manganese oxide produces a gas. He called the gas "fire air" because of the brilliant sparks it produced when it came in contact with hot charcoal dust. He repeated this experiment by heating potassium nitrate, mercury oxide, and many other materials and produced the same gas. He collected the gas in pure form using a small bag. He explained the properties of �fire air� using the phlogiston theory, which was soon discredited by Lavoisier. He carefully recorded his experiments in his notes, but waited several years before publishing them. In 1774, Priestley repeated Scheele�s experiments using a 12-inch-wide glass "burning lens", he focused sunlight on a lump of reddish mercuric oxide in an inverted glass container. The gas emitted, he found, was "five or six times as good as common air." (1) In succeeding tests, it caused a flame to burn intensely and kept a mouse alive about four times as long as a similar quantity of air.

Priestley, a big supporter of the phlogiston theory, called his discovery "dephlogisticated air" on the theory that it supported combustion so well because it had no phlogiston in it, and hence could absorb the maximum amount during burning. Repeat Scheele�s and Priestley experiments: Warning: Heating up materials and breathing vapors could be very dangerous. As a rule: this experiment should be performed under the supervision of teachers or adults familiar with safety procedures. Consult your teacher or other knowledgeable adults and experts about how to obtain the mentioned materials and how to use them properly and safely in this experiment. Do not do this experiment alone! Consult the link section and further resources provided. Ensure that you understand the basic principals. Surf the web and consult your local library, your teacher and other knowledgeable adults and experts. Oxygen from Plants In August of 1771, Joseph Priestley , put a sprig of mint into a transparent closed space with a candle that burned out the air until it soon went out. After 27 days, he relit the extinguished candle again and it burned perfectly well in the air that previously would not support it.

And how did Priestley light the candle if it was placed in a closed space? He focused sun light beams with a mirror onto the candle wick (Priestley had no bright source of light, and had to rely on the sun). Today, of course, we can use more sophisticated methods to light the candle like focusing light from a flood light through converging lens, or by an electrical spark. So priestly proved that plants somehow change the composition of the air. In another celebrated Experiment from 1772, Priestley kept a mouse in a jar of air until it collapsed. He found that a mouse kept with a plant would survive. However, we do not recommend to repeat this experiment and hurt innocent animals. These kinds of observations led Priestley to offer an interesting hypothesis that plants restore to the air whatever breathing animals and burning candles remove - what was later coined by Lavoisier "oxygen". In these experiments, Priestly was the first to observe that plants release oxygen into the air - the process known to us as photosynthesis .

Repeat Joseph Priestley's Experiments: Joseph Priestley, Discoverer of Oxygen National Historic Chemical Landmark - American Chemical Society American Chemical Society Joseph Priestley, Discoverer of Oxygen Joseph Priestley and the Discovery of Oxygen International Historic Chemical Landmark Dedicated August 1, 1994, at the Joseph Priestley House in Northumberland, Pennsylvania, USA, and August 7, 2000, at Bowood House in Wiltshire, UK. Landmark Lesson Plan: Joseph Priestley, Discoverer of Oxygen When Joseph Priestley discovered oxygen in 1774, he answered age-old questions of why and how things burn. An Englishman by birth, Priestley was deeply involved in politics and religion, as well as science. When his vocal support for the American and French revolutions made remaining in his homeland dangerous, Priestley left England in 1794 and continued his work in America until his death. Contents “Joseph Priestley Discoverer of Oxygen” commemorative booklet produced by the National Historic Chemical Landmarks program of the American Chemical Society in 2004 (PDF).

About Joseph Priestley Some 2,500 years ago, the ancient Greeks identified air — along with earth, fire and water — as one of the four elemental components of creation. That notion may seem charmingly primitive now. But it made excellent sense at the time, and there was so little reason to dispute it that the idea persisted until the late 18th century. It might have endured even longer had it not been for a free-thinking English chemist and maverick theologian named Joseph Priestley. Priestley (1733-1804) was hugely productive in research and widely notorious in philosophy. He invented carbonated water and the rubber eraser, identified a dozen key chemical compounds, and wrote an important early paper about electricity. His unorthodox religious writings and his support for the American and French revolutions so enraged his countrymen that he was forced to flee England in 1794. He settled in Pennsylvania, where he continued his research until his death. The world recalls Priestley best as the man who discovered oxygen, the active ingredient in our planet's atmosphere.

In the process, he helped dethrone an idea that dominated science for 23 uninterrupted centuries: Few concepts "have laid firmer hold upon the mind," he wrote, than that air "is a simple elementary substance, indestructible and unalterable." In a series of experiments culminating in 1774, Priestley found that "air is not an elementary substance, but a composition," or mixture, of gases. Among them was the colorless and highly reactive gas he called "dephlogisticated air," to which the great French chemist Antoine Lavoisier would soon give the name "oxygen." It is hard to overstate the importance of Priestley's revelation. Scientists now recognize 92 naturally occurring elements-including nitrogen and oxygen, the main components of air. They comprise 78 and 21 percent of the atmosphere, respectively. Engraving of Joseph Priestley by Charles Turner, after a painting by Henry Fuseli. Courtesy The Edgar Fahs Smith Memorial Collection, The University of Pennsylvania Libraries. Understanding the Composition of Air In the mid-18th century, the concept of an element was still evolving.

Researchers had distinguished no more than two dozen or so elements, depending on who was doing the counting. It wasn't clear how air fit into that system. Nobody knew what it was, and researchers kept finding that it could be converted into such a variety of forms that they routinely spoke of different "airs." The principal method for altering the nature of air, early chemists learned, was to heat or burn some compound in it. The second half of the 1700s witnessed an explosion of interest in such gases. The steam engine was in the process of transforming civilization, and scientists of all types were fascinated with combustion and the role of air in it. British chemists were especially prolific. In 1754, Joseph Black identified what he called "fixed air" (now known to be carbon dioxide) because it could be returned, or fixed, into the sort of solids from which it was produced.

In 1766, a wealthy eccentric named Henry Cavendish produced the highly flammable substance Lavoisier would name hydrogen, from the Greek words for "water maker." Finally in 1772, Daniel Rutherford found that when he burned material in a bell jar, then absorbed all the "fixed" air by soaking it up with a substance called potash, a gas remained. Rutherford dubbed it "noxious air" because it asphyxiated mice placed in it. Today, we call it nitrogen. But none of those revelations alone tells the whole story. The next major discovery would come from a man whose early life gave no indication that he would become one of the greatest experimental chemists in history. Back to top Bubbling Beverages In 1767, Priestley was offered a ministry in Leeds, Englane, located near a brewery. This abundant and convenient source of "fixed air” — what we now know as carbon dioxide — from fermentation sparked his lifetime investigation into the chemistry of gases. He found a way to produce artificially what occurred naturally in beer and champagne: water containing the effervescence of carbon dioxide.

The method earned the Royal Society's coveted Copley Prize and was the precursor of the modern soft-drink industry. Oxygen and Other Discoveries in England Joseph Priestley was born in Yorkshire, the eldest son of a maker of wool cloth. His mother died after bearing six children in six years. Young Joseph was sent to live with his aunt, Sarah Priestley Keighley, until the age of 19. She often entertained Presbyterian clergy at her home, and Joseph gradually came to prefer their doctrines to the grimmer Calvinism of his father. Before long, he was encouraged to study for the ministry. And study, as it turned out, was something Joseph Priestley did very well. Aside from what he learned in the local schools, he taught himself Latin, Greek, French, Italian, German and a smattering of Middle Eastern languages, along with mathematics and philosophy. This preparation would have been ideal for study at Oxford or Cambridge, but as a Dissenter (someone who was not a member of the Church of England) Priestley was barred from England's great universities. So he enrolled at Daventry Academy, a celebrated school for Dissenters, and was exempted from a year of classes because of his achievements.

After graduation, he supported himself, as he would for the rest of his life, by teaching, tutoring and preaching. His first full-time teaching position was at the Dissenting Academy in Warrington. (Although obviously brilliant, original, outspoken and, by one report, of "a gay and airy disposition," Priestley had an unpleasant voice and a sort of stammer. That he made a living through lectures and sermons is further evidence of his extraordinary nature.) In 1762, he was ordained and married Mary Wilkinson, the daughter of a prominent iron-works owner. She was, he noted, "of an excellent understanding, much improved by reading, of great fortitude and strength of mind, and of a temper in the highest degree affectionate and generous; feeling strongly for others and little for herself." Priestley traveled regularly to London, and became acquainted with numerous men of science and independent thought, including an ingenious American named Benjamin Franklin, who became a lifelong friend. Franklin encouraged Priestley in his research, one result of which was The History and Present State of Electricity. For that work, and his growing reputation as an experimenter, Priestley was made a Fellow of the Royal Society in 1766.

The History book was too tough for a popular audience, and Priestley determined to write a more accessible one. But he could find no one to create the necessary illustrations. So, in typical fashion, he taught himself perspective drawing. Along the way, he made many mistakes, and discovered that India rubber would erase lead pencil lines — a fact he mentioned in the preface. By the age of 34, Priestley was a well-established and respected member of Britain's scientific community. He was still paying a price for his religious nonconformity, however. When the explorer Captain James Cook was preparing for his second voyage, Priestley was offered the position of science adviser. But the offer was rescinded under pressure from Anglican authorities who protested his theology, which was evolving into a strongly Unitarian position that denied the doctrine of the trinity. In retrospect, the Cook affair may have been all for the best. In 1773, the Earl of Shelburne asked Priestley to serve as a sort of intellectual companion, tutor for the earl's offspring, and librarian for his estate, Bowood House.

The position provided access to social and political circles Priestley could never have gained on his own, while leaving ample free time for the research that would earn him a permanent place in scientific history. He systematically analyzed the properties of different "airs" using the favored apparatus of the day: an inverted container on a raised platform that could capture the gases produced by various experiments below it. The container could also be placed in a pool of water or mercury, effectively sealing it, and a gas tested to see if it would sustain a flame or support life. In the course of these experiments, Priestley made an enormously important observation. A flame went out when placed in a jar in which a mouse would die due to lack of air. Putting a green plant in the jar and exposing it to sunlight would "refresh" the air, permitting a flame to burn and a mouse to breathe. Perhaps, Priestley wrote, "the injury which is continually done by such a large number of animals is, in part at least, repaired by the vegetable creation." Thus he observed that plants release oxygen into the air — the process known to us as photosynthesis. On August 1, 1774, he conducted his most famous experiment.

Using a 12-inch-wide glass "burning lens," he focused sunlight on a lump of reddish mercuric oxide in an inverted glass container placed in a pool of mercury. The gas emitted, he found, was "five or six times as good as common air." In succeeding tests, it caused a flame to burn intensely and kept a mouse alive about four times as long as a similar quantity of air. Priestley called his discovery "dephlogisticated air" on the theory that it supported combustion so well because it had no phlogiston in it, and hence could absorb the maximum amount during burning. (The year before, Swedish apothecary Carl Wilhelm Scheele isolated the same gas and observed a similar reaction. Scheele called his material "fire air." But his findings were not published until 1777.) Whatever the gas was called, its effects were remarkable. "The feeling of it in my lungs," Priestley wrote, "was not sensibly different from that of common air, but I fancied that my breast felt peculiarly light and easy for some time afterwards. Who can tell but that in time, this pure air may become a fashionable article in luxury.

Hitherto only two mice and myself have had the privilege of breathing it." Back to top Phlogiston and Fire In the mid-18th century, the most pressing issue in chemistry and physics was to determine what exactly happens when something burns. The prevailing theory was that flammable materials contained a substance called “phlogiston” (from the Greek word for burn) that was released during combustion. The theory held that when a candle burned, for example, phlogiston was transferred from it to the surrounding air. When the air became saturated with phlogiston and could contain no more, the flame went out. Breathing, too, was a way to remove phlogiston from a body. A typical test for the presence of phlogiston was to place a mouse in a container and measure how long it lived. When the air in the container could accept no more phlogiston, the mouse would die. The 19th century scientist Antoine Lavoisier disproved the existence of phlogiston and helped to form the basis of modern chemistry using Joseph Priestley’s discovery of oxygen. Pneumatic trough and other equipment used by Joseph Priestley in his experiments on oxygen and other gases.

Reproduced from Joseph Priestley's book Experiments and Observations on Different Kinds of Air, 1774-1786. Religion and Emigration to America As luck would have it, Lord Shelburne was setting off on a trip to the European continent and took Priestley along. In France, Priestley met Lavoisier and described his discovery. It turned out to be the clue Lavoisier needed to develop his theory of chemical reactions — the "revolution" in chemistry that would finally dispel the phlogiston theory. Burning substances, Lavoisier argued, did not give off phlogiston; they took on Priestley's gas, which Lavoisier called "oxygen" from the Greek word for acid-maker. By then, however, Priestley had returned to England, where he escalated his support for the American Revolution and for highly unorthodox religious views. Those positions were a source of embarrassment for Lord Shelburne. Priestley left his service in 1780, moving to Birmingham and taking a position as head of a liberal congregation called New Meeting.

His new location brought him into contact with numerous luminaries including Erasmus Darwin, grandfather of Charles, the great architect of evolutionary theory. James Watt and Matthew Boulton — who were about to transform society with their steam engine — were there, as was Josiah Wedgwood, the famous potter, who supported Priestley's chemical experiments. Birmingham also boasted a distinguished scientific discussion group, the Lunar Society, which met on nights of a full moon so that the members could see their way home. Priestley's encouragement of the French Revolution, together with his increasingly controversial theology and attacks on the doctrine of the trinity, eventually became too notorious for safety. In 1791, an alcohol-fueled mob of royalists burned the New Meeting house, and then Priestley's home. The scientist and his family barely escaped. They fled to London, but eventually it proved no safer. Priestley's sons could not find work and emigrated to Pennsylvania, where they hoped to found a center for free-thinking Englishmen. Finally Joseph and Mary followed them, setting sail for America on April 8, 1794.

Priestley turned down the offer of a teaching position at the University of Pennsylvania in Philadelphia, and instead built a house in the remote hamlet of Northumberland to be near his sons. The area was decidedly rustic. There Priestley continued his research, isolating carbon monoxide (which he called "heavy inflammable air") and founding the Unitarian Church in the United States. For the most part, he led a quiet and reflective life — especially after his friend Thomas Jefferson was elected president in 1800. During his final trip to Philadelphia, he told the Philosophical Society that "having been obliged to leave a country which has been long distinguished by discoveries in science, I think myself happy by my reception in another which is following its example, and which already affords a prospect of its arriving at equal eminence." His words proved prophetic. A colloquium held on the centennial of Priestley's discovery of oxygen led to the founding of the American Chemical Society —today the world's largest scientific society — in 1876. On February 3, 1804, Priestley began an experiment, but found himself too weak to continue. He went to his bed in his library, never again to emerge.

On February 6, he summoned one of his sons and an assistant. He dictated some changes in a manuscript. When he was satisfied with the revisions, he said "That is right. I have now done." Minutes later he died painlessly, ending what Jefferson called "one of the few lives precious to mankind." Anti-Priestley cartoon reading "Doctor Phlogiston, The Priestley politician or the Political Priest!" Reproduced courtesy of the Library of the Royal Society of Chemistry. Portrait of Joseph Priestley (undated). Reproduced courtesy of the Library of the Royal Society of Chemistry. Landmark Designation and Acknowledgments Landmark Designation The American Chemical Society dedicated the Joseph Priestley House a National Historic Chemical Landmark on August 1, 1994. The plaque commemorating the event reads: Joseph Priestley (1733-1804) — Unitarian minister, teacher, author, natural philosopher, discoverer of oxygen, and friend of Benjamin Franklin and Thomas Jefferson — supervised the construction of this house and laboratory from 1794 to 1798, then lived and worked here until his death in 1804.

His library of some 1,600 volumes and his chemical laboratory, where he first isolated carbon monoxide, were probably the best in the country at that time. As suggested by Edgar Fahs Smith in 1920, the Joseph Priestley House has become "a Mecca for all who would look back to the beginnings of chemical research" in America. The American Chemical Society and the Royal Society of Chemistry dedicated the Discovery of Oxygen by Joseph Priestley an International Historic Chemical Landmark on August 7, 2000, in Wiltshire, UK. The plaque commemorating the event reads: Joseph Priestley (1733-1804) — Unitarian minister, teacher, author, and natural philosopher — was the Earl of Shelburne's librarian and tutor to his sons. In this room, then a working laboratory, Priestley pursued his investigations of gases. On 1 August 1774 he discovered oxygen. Twenty years later he emigrated to America where he continued his research at his home and laboratory in Northumberland, Pennsylvania.

Acknowledgments: Adapted for the internet from “The Joseph Priestley House,” produced by the National Historic Chemical Landmarks program of the American Chemical Society in 1994 and “Bowood House,” produced by the National Historic Chemical Landmarks program of the American Chemical Society and the Royal Society of Chemistry in 2000. Back to top Cite this Page American Chemical Society International Historic Chemical Landmarks. Discovery of Oxygen by Joseph Priestley. (accessed Month Day, Year). IB Chemistry: Who discovered oxygen? Who discovered oxygen? Monday 27 January 2014 View all posts In the new Guide for first teaching in 2014 under Stoichiometric relationships, it states in the Theory of Knowledge part of 1.1 “Lavoisier’s discovery of oxygen, which overturned the phlogiston theory of combustion, is an example of a paradigm shift. How does scientific knowledge progress?” This seems a strange statement to me as it is generally accepted that Lavoisier did not discover oxygen. Attributing who made the first discovery of many scientific findings can be notoriously difficult and contentious.

For example, was it Alexander Fleming who first discovered penicillin as most texts and websites claim or was it Clodomiro Twight, a Costa Rican? Often it is nationalistic and political factors which determine who history credits with the first discovery. Fleming worked at St Mary’s Hospital, Paddington where the newspaper magnate Lord Beaverbrook had connections and Beaverbrook used his newspapers to publicise Fleming’s work even though Clodomiro Twight published his finding before Fleming. Similar controversy surrounds the discovery of oxygen. Certainly the first publication of the discovery appears to have been made by Joseph Priestly. It seems likely that Priestly first isolated what he called ‘dephlogisticated air’ in August 1774 at Bowood House in the UK. Later that year while he was in Paris he replicated his experiment for Antoine Lavoisier. In March he communicated his discovery in letters to several people and read out a paper to the Royal Society which was published in the Society’s Journal Philosophical Transactions (An Account of further Discoveries in Air, 65 (1775): 384–94).

His preparation of oxygen was achieved by heating mercury oxide by using a lens to focus the sun’s rays on the oxide and then he showed that mice survived when exposed to the gas produced, He also breathed the ‘dephlogisticated air’ in himself and wrote that it was” five or six times better than common air for the purpose of respiration and inflammation”. In fact it seems probable that the first discovery of oxygen was made some two years earlier than Priestly by a Swedish scientist, Carl Wilhelm Scheele. Scheele obtained oxygen by heating not only mercuric oxide but also some metal nitrates and called the gas ‘fire air’ because it supported combustion. Scheele wrote about this in a manuscript sent to his publisher in 1775 but the work, Treatise on Air and Fire, was only published in 1777. So why has the IB listed only Lavoisier as the discoverer of oxygen?

Priestly showed his experiment to Lavoisier in 1774 and Scheele posted a letter to Lavoisier detailing his discovery on 30 September 1774 (A copy of this letter was found after Scheele’ death, although Lavoisier claimed to have never seen it). There seems little doubt that Lavoisier did not independently discover oxygen and to some extent was culpable of academic dishonesty by not acknowledging the work of others. However what he did do was to realise the significance of the discovery. He was the first to call ‘dephlogisticated air’ and ‘fire air’ oxygen which he derived from the Greek meaning producer of sharp taste as he thought that all acids contained oxygen. He also used quantitative chemistry to show that during combustion substances combine with oxygen and thus conclusively disproved the phlogiston theory. There is a lot of good TOK in the statement in 1.1 of the new programme but for the IB Chemistry programme to imply that it was Lavoisier alone who discovered oxygen is patently misleading.

Joseph Priestley - Chemistry Encyclopedia - water, metal, gas, number Joseph Priestley - Chemistry Encyclopedia ENGLISH THEOLOGIAN AND CHEMIST 1733–1804 Joseph Priestley was a dissenting Unitarian minister in England at a time when adherence to the established Church of England was of great importance. Preaching was a difficult career for Priestley—because his Unitarian views were unpopular and because he spoke with a stammer. Priestley published widely in a variety of subjects, including theology, education, history, politics, and science. Most often, Priestley is remembered as one of the discoverers of oxygen, but his impact on other lives went much further than this. English chemist Joseph Priestley, the first person to isolate a number of gases, including oxygen. His first major science publication was The History and Present State of Electricity (1767), which gained him admission to the Royal Society ; it was followed by The History and Present State of Discoveries Relating to Vision, Light and Colours (1772).

Both light and electricity were regarded as aspects of the Newtonian "imponderable fluid" or "ether." They were called "imponderable fluids" (or subtle fluids) because they had no detectable weight (no "poundage"), but still had some fluidlike characteristics. Another form of this "ether" was "phlogiston." Phlogiston was the postulated substance of fire, the active principle of acids, and the driving force behind chemical reactions. As Priestley expanded his studies in chemistry he became active in the field of pneumatic chemistry, the study of air and gases. Priestley was the first to isolate and characterize a number of gases, including oxygen, nitrogen, hydrogen chloride, ammonia, sulfur dioxide, carbon monoxide, nitric oxide , and nitrous oxide. Priestley's names for these compounds were different from the modern names, in part because he never adopted the oxygen theory of chemistry. The names he used were in terms of the older "phlogiston theory." Priestley did this work using very simple apparatuses, such as saucers, glasses, tubes, cylinders, and tubs of water or mercury.

Among the chemical phenomena he investigated was the behavior of a gas or other substance in contact with fire. If fire was the visible escape of phlogiston from a burning substance, then some gases had a greater affinity for phlogiston than ordinary air and encouraged the flame. Other gases had a lesser affinity for phlogiston than ordinary air (or no affinity at all) and would extinguish the flame. One gas was found to be especially able to support a flame. Priestley called this gas "eminently respirable air." He later called this same substance "dephlogisticated air," reasoning that because it had a large affinity for phlogiston, it must be particularly devoid of it, or dephlogisticated. Priestley found that the heating of a sample of "red precipitate" (a calx of mercury) to produce pure mercury generated very pure dephlogisticated air. Priestley's discovery of the large amount of "air" generated during the heating of red precipitate was similar to Joseph Black's discovery of "fixed air." The production of dephlogisticated air also fit Priestley's belief that a metal is phlogiston compounded with a calc.

The dephlogisticated air liberated from red precipitate also fit well with the observation that when a candle burned out in a closed vessel, the volume of the air was diminished. It was thought that the presence of phlogiston decreased the "springiness" of air. Thus, adding phlogiston to air would cause it to contract, and removing phlogiston from air would cause it to expand. Priestley also found that air saturated with phlogiston could be "revivified" (or dephlogisticated) by green plants in the presence of sunlight. Dephlogisticated air would be renamed "oxygen" by Antoine Lavoisier, who made it the cornerstone of his theory of chemistry. Priestley resisted the oxygen theory of chemistry to the end of his life. For Priestley, phlogiston was more than just the active principle of fire—it was the active principle of life. Here Priestley's scientific theory merged with some of his religious beliefs. If phlogiston were the active principle of fire, heat, light, electricity, acids, chemical reactivity, and life, then it might also be the active principle of spirit.

This accorded well with his Unitarian belief in one omnipresent active principle in the universe. In his book Disquisition on Matter and Spirit (1777), he asserted that there was only matter and void in the universe—there were no immaterial spiritual influences. Thus, the material existence of phlogiston corresponded well with his religious beliefs. Priestley also had strong convictions in favor of broad-based democratic reforms and freedom of thought. He advocated wider religious toleration in England. He supported the American colonists in their revolution against the British Crown and supported the French Revolution, even in the face of atrocities such as the Reign of Terror. Priestley made enemies as a result of his political beliefs, and in 1791 his house and laboratory in Birmingham were attacked and burned by a mob. Priestley fled to London and was able to emigrate from there to the United States in 1794. In the United States he was a renowned international figure. When he landed in New York, both the mayor and the governor greeted him. When he arrived in Philadelphia, he was received by President Washington. In 1794 Priestley declined an offer to be a professor of chemistry at the University of Pennsylvania.

He retired from public life in Northumberland, Pennsylvania, and died there in 1804. His home in Northumberland is now preserved as a historical landmark. According to Peter Miller (1993), "A work entitled 'Joseph Priestley in Context' would . . . far surpass the competence of any single chronicler." PHLOGISTON There never was a widespread coherent theory of phlogiston. German chemist Johann J. Becher (1635–1682) brought the term "phlogiston" into use among European chemists in the middle 1600s. The word is based upon a Greek word used by Aristotle in his writings on matter. German chemist Georg Stahl (1660–1734) further articulated the phlogiston theory in the early 1700s. According to the phlogiston theory, a flame was thought to be the visible escape of matter called phlogiston from a burning substance. Another key feature of the theory was that a metal was thought to be composed of phlogiston and earth.

Luster, high heat conductivity, malleability, and ductility are all unusual characteristics for metals, but according to the theory, metals share these features because of their postulated phlogiston content. If the phlogiston was removed from a metal, the result was an earth called calc (plural, calx), often the metal's naturally occurring ore. Under certain conditions, phlogiston might even exhibit a negative weight! This anomaly became problematic after Sir Isaac Newton's 1687 Law of Universal Gravitation. —David A. Bassett General Chemistry Online: FAQ: History of chemistry: When did Antoine Lavoisier discover oxygen? Next Question When did Antoine Lavoisier discover oxygen? Antoine Lavoisier was never credited with the discovery of any element. Nor does he deserve that honor. The dates and events surrounding the discovery of oxygen offer the following blunt reminders to anyone seeking a place in scientific posterity: Document and date your work. Recognize the importance of your discovery. Interpret your work correctly and thoroughly, or you may not receive credit for it. Tell someone what you've done. Tell the community, not just a colleague. Acknowledge your competitors.

1771-1772 Carl Wilhelm Scheele discovered that red-hot manganese oxide (MnO2) produces a gas. He called the gas "fire air" because of the brilliant sparks it produced when it came in contact with hot charcoal dust. He recognized that heating mercuric oxide produced the same gas. The reaction is now known to be 2 HgO(s) 2 Hg( ) + O2(g) He collected the gas in pure form using a small bag. He explained the properties of fire air using the phlogiston theory, which was soon discredited by Lavoisier. He carefully recorded the experiment in his notes, but waited several years before publishing them. April, 1774 Pharmacist Pierre Bayen discovers that heating mercury oxides resulted in a discharge of gas and a loss of mass. He collected the gas, and noted that it was slightly denser than air. Bayen was timid about publishing anything but direct observations. He did not interpret his results and he did not examine the gas further. Had he done so, he would have realized that the gas he had collected was not ordinary air.

He realized his mistake after Lavoisier published his work, and tried to lay claim to the discovery, but he was too late. He has been forgotten by history. August 1, 1774 Joseph Priestley independently repeats the production of oxygen from mercuric oxide in his laboratory at Lord Shelburne's country mansion near Calne, England. He wrote, "What surprised me more than I can well express, was that a candle burned in this air with a remarkably vigorous flame..." Priestley carefully documented his work, recognized the significance of what he had done, and published his results promptly. Posterity gives Priestley credit for the discovery of oxygen. September 16, 1774 Lavoisier observes that heating mercuric oxide produces metallic mercury. He thought the reaction might have been caused by contact with iron; he made no note of gas evolution in his notebook. October 15, 1774 Lavoisier received a letter from Scheele that carefully described the preparation of "fire air" by heating silver carbonate. Lavoisier never answered the letter.

October 1774 Priestley visits Lavoisier in Paris and discussed his experiments with the decomposition of mercuric oxide over dinner. In 1800, he recalled that dinner at Lavoisier's house: Having made the discovery some time before I was in Paris, in the year 1774, I mentioned it at the table of Mr. Lavoisier, when most of the philosophical people of the city were present, saying that it was a kind of air in which a candle burned much better than in common air, but that I had not then given it a name. At this, all the company, and Mr. and Mrs. Lavoisier as much as any, expressed great surprise. March 8, 1775 Priestley demonstrates that sealed containers of the new gas can support life longer than atmospheric air. He called the gas "dephlogisticated air", using terminology and ideas from the soon-to-be-discredited phlogiston theory to explain his observations. He tried breathing the gas himself, and reported that he felt "peculiarly light and easy for some time afterwards.

Who can tell but that, in time, this pure air may become a fashionable article in luxury." April, 1775 Lavoisier announced to the Academy of Science in Paris that he had isolated a component of air that he called "eminently breathable air" by decomposition of mercuric oxide. (Carmen Giunta has published Lavoisier's paper in his collection of classic papers from the history of chemistry. Giunta highlights changes in the paper between 1775 and its actual publication date in 1778.) 1777 Scheele reports his preparation of oxygen in his Treatise on Fire and Air. He was aware of Priestley's and Lavoisier's claims, but he did not make any claim of his own. Lavoisier biographer Jean-Pierre Poirier describes Scheele as "self-effacing" and speculates that Scheele did not want to be accused of plagiarism- even though the discovery was rightly his! Scheele does receive parenthetical credit today. 1789 In his Traité Élémentaire de Chimie, Lavoisier describes the preparation of oxygen in detail by heating the red oxide of mercury.

Lavoisier refers to oxygen as "this air, which Mr. Priestley, Mr. Scheele, and I discovered about the same time" [ Partington ]. Priestley denounced Lavoisier's claim in his book Experiments and Observations on Different Kinds of Air, saying that Lavoisier had borrowed his idea for preparing oxygen from mercuric oxide, and had not clearly realized at the time that oxides contained only a component of atmospheric air, not atmospheric air in whole. Lavoisier's attempt to wrestle credit for the discovery from Priestley was witnessed by his colleague Edmond Genet [ Poirier ]: I also had the advantage during my stay at Birmingham of becoming acquainted with Dr. Priestley who had the kindness to repeat for my gratification his most interesting experiments on air and gases of which I sent an account to the Academy of Paris. At that time, Lavoisier was pursuing the same subject, and I was surprised on my return to hear him read a memorial at one of the sittings of the Academy which was simply a repetition in different words of Priestley's experiments which I had reported.

He laughed, and said to me, "My friend, you know that those who start the hare do not always catch it." References Priestley, Joseph (1733-1804) -- from Eric Weisstein's World of Scientific Biography Priestley, Joseph (1733-1804) English chemist and amateur natural philosopher whose scientific works covered physics, electricity, magnetism, and optics, in addition to chemistry. The objects of his chemical studies included "fixed air" (carbon dioxide), "nitrous air" (nitric oxide), "marine acid air" (hydrogen chloride), "alkaline air" (ammonia), "vitriolic air" (sulfur dioxide), "phlogisticated nitrous air" (nitrous oxide, laughing gas), and "dephlogisticated air" (oxygen). Priestley was a firm believer in phlogiston.

His chemical writings were published in the three volume Experiments and Observations on Different Kinds of Airs (1774- 1777) and in the three volume Experiments and Observations Relating to Various Branches of Natural Philosophie (1779-1786). Priestley is credited with the discovery of oxygen in 1774, which he produced by focusing sunlight on mercuric oxide. He experimented with dephlogisticated air, noticing that it made himself and animals light-headed. By dissolving fixed air in water, he invented carbonated water. He also noticed that the explosion of inflammable air with common air produced dew. Lavoisier repeated this experiment and took credit for it. Priestley believed in the phlogiston theory, and was convinced that his discovery of oxygen proved it to be correct. He was a politically involved Unitarian preacher and sympathizer with the French Revolution, two facts which forced him and his family to move to America in 1794. At Benjamin Franklin's suggestion, Priestley demonstrated the lack of force inside a charged spherical shell and deduced from this the r-2 law of electric force.

This agreed with the results of John Robinson and was later given the name Coulomb's law in commemoration of Coulomb's independent result. © 1996-2007 Eric W. Weisstein Discovering Oxygen: A Brief History | Mental Floss Discovering Oxygen: A Brief History Image credit: Like us on Facebook Because there are three different dead guys who regularly vie for credit for discovering oxygen, we’ve staged a little friendly competition to establish which of these great men deserves the title of the O-master. In evaluating the contenders, we’ll look at when they isolated oxygen and how their experiments furthered our understanding of the element. In addition to bragging rights, the winner takes home one zillion liters of oxygen. Contender 1: Carl Wilhelm Scheele Nationality: Swedish Occupation: Apothecary Biggest Accomplishment: In 1772, he was the first person to figure out a way – actually a couple of ways - to isolate oxygen. He discovered that mercuric oxide, silver carbonate, magnesium nitrate, and potassium nitrate all gave off the same gas when heated.

Scheele dubbed the mystery element “fire air” because he noticed that it produced sparks when it came into contact with charcoal dust. Other Biggest Accomplishment: Discovered chlorine Biggest Shortcoming: Bad timing. Scheele didn’t publish his discovery until 1777, in a treatise called Chemical Observations and Experiments on Air and Fire. By that time, Joseph Priestley had already written a paper describing his findings and published the comprehensive Experiments and Observations on Air. Lavoisier had also successfully isolated the gas. Because Scheele waited so long to get the word out, his groundbreaking experiment was often overlooked by other scientists, earning him the nickname “Hard Luck Scheele.” Contender 2: Joseph Priestley Nationality: British Occupation: Radical Unitarian Minister Biggest accomplishment: In 1771, Priestley noticed that a mouse in a sealed jar would eventually collapse. He then tried slipping a sprig of mint inside and realized the plant magically revived his subject. Realizing that plants did something to freshen up the air, he wrote to his friend Benjamin Franklin, saying he hoped his discovery would stop people from cutting down so many trees.

Priestley didn’t actually isolate this mystery gas until August 1, 1774, when he heated some mercuric oxide powder and discovered that it gave off a gas that could reignite a glowing ember. He collected large amounts of the gas and tried breathing it himself. After a few puffs, Priestley was hooked. He declared, “My breast felt peculiarly light and easy for some time afterward.” Other Biggest Accomplishment: Invented seltzer water Biggest Shortcoming: Priestley just wouldn’t let go of phlogiston theory – a crackpot hypothesis that argued combustion was fueled by an invisible substance called phlogiston. Priestley believed that his mystery gas supported combustion because it was pure and could absorb phlogiston released by burning substances. That’s why he was pushing to name oxygen “dephlogisticated air.” Contender 3: Antoine Laurent Lavoisier Nationality: French Occupation: Tax farmer/Commissioner of the Royal Gunpowder and Saltpeter Administration Biggest Accomplishment: Lavoisier debunked phlogiston theory. Up until then, scientists couldn’t explain why tin gained weight when it was burned; if it was releasing phlogiston, it should lose weight.

Lavoisier realized that there was no way phlogiston could have a negative mass and set out to prove that combustion was caused by something else. He heated Mercury until calx formed, then he heated the calx until it gave off a clear gas. Lavoisier realized combustion resulted from a chemical reaction with this gas – not some flammable mystery element called phlogiston. He dubbed the gas “oxygen” – a name that referred to its ability to create acids. Other Biggest Accomplishment: Helped establish this thing called the metric system, which some people supposedly use. Biggest Shortcoming: Lavoisier might have been the one to name oxygen, and for that, we’re grateful (nobody would be caught dead in a dephlogisticated air bar). However, he was not the first to isolate the gas or recognize its unique properties. His methods weren’t even original. In fact, Lavoisier had been in contact with both Priestley and Scheele and borrowed from their experiments. And the O-Master Is... We’re giving this one to Joseph Priestley. Although he gets points for publishing first, his real breakthrough was his realization that plants gave off oxygen.

This discovery enabled future scientists to understand cellular respiration and photosynthesis – both of which are absolutely essential to life on Earth. We’re also giving Priestley points for recognizing the commercial potential of oxygen when he anticipated that the pure air could be a hit at parties. Sure enough, over 200 years later, oxygen bars have become a thing! So next time you take a breath (hopefully soon), think of Joseph Priestley and his iconic experiment, which took place exactly 238 years ago today. The room (laboratory) where Joseph Priestley discovered Ox… | Flickr en.wikipedia.org/wiki/Joseph_Priestley In August 1774 he isolated an "air" that appeared to be completely new, but he did not have an opportunity to pursue the matter because he was about to tour Europe with Shelburne. While in Paris, however, Priestley managed to replicate the experiment for others, including French chemist Antoine Lavoisier. After returning to Britain in January 1775, he continued his experiments and discovered "vitriolic acid air" (sulfur dioxide, SO2). In March he wrote to several people regarding the new "air" that he had discovered in August.

One of these letters was read aloud to the Royal Society, and a paper outlining the discovery, titled "An Account of further Discoveries in Air", was published in the Society's journal Philosophical Transactions. Priestley called the new substance "dephlogisticated air"; he first tested it on mice, who surprised him by surviving quite a while entrapped with the air, and then on himself, writing that it was "five or six times better than common air for the purpose of respiration, inflammation, and, I believe, every other use of common atmospherical air". He had discovered oxygen gas (O2). Priestley assembled his oxygen paper and several others into a second volume of Experiments and Observations on Air, published in 1776. He did not emphasize his discovery of "dephlogisticated air" (leaving it to Part III of the volume) but instead argued in the preface how important such discoveries were to rational religion. His paper narrated the discovery chronologically, relating the long delays between experiments and his initial puzzlements; thus, it is difficult to determine when exactly Priestley "discovered" oxygen.

Such dating is significant as both Lavoisier and Swedish pharmacist Carl Wilhelm Scheele have strong claims to the discovery of oxygen as well, Scheele having been the first to isolate the gas (although he published after Priestley) and Lavoisier having been the first to describe it as purified "air itself entire without alteration" (that is, the first to explain oxygen without phlogiston theory). In his paper "Observations on Respiration and the Use of the Blood", Priestley was the first to suggest a connection between blood and air, although he did so using phlogiston theory. In typical Priestley fashion, he prefaced the paper with a history of the study of respiration. A year later, clearly influenced by Priestley, Lavoisier was also discussing respiration at the Académie des sciences. Lavoisier's work began the long train of discovery that produced papers on oxygen respiration and culminated in the overthrow of phlogiston theory and the establishment of modern chemistry. Around 1779 Priestley and Shelburne had a rupture, the precise reasons for which remain unclear. Shelburne blamed Priestley's health, while Priestley claimed Shelburne had no further use for him.

Some contemporaries speculated that Priestley's outspokenness had hurt Shelburne's political career. Schofield argues that the most likely reason was Shelburne's recent marriage to Louisa Fitzpatrick—apparently, she did not like the Priestleys. Although Priestley considered moving to America, he eventually accepted Birmingham New Meeting's offer to be their minister. Done

Question: Which chemist discovered oxygen in 1774, calling it 'dephlogisticated air'?
Answer: JOSEPH PRIESTLY